1. Field of the Invention
The invention concerns a temperature-resistant, tightly sealed cable bushing in a housing, in particular in a gas sensor housing, with a molded body arranged inside the housing, through which at least one connecting cable with an electrical conductor and a cable insulation are fed, as well as a method for the manufacture of said cable bushing.
2. Description of the Related Art
Tightly sealed and high-temperature resistant cable bushings are required, for example, for gas sensors, in particular for Lambda probes. These gas sensors have a housing with a sensor element arranged on the inside. The sensor element is contacted inside the housing with connecting cables. The connecting cables exit the housing through a cable bushing. The gas sensors for determining the exhaust-gas composition in motor vehicles are inserted into the exhaust pipe and are thus subjected to the environmental influences prevalent there. The sensor element arranged inside the housing operates as a rule with reference air, which is fed into the housing, for example, via the cable insulation. However, it is critical on the other hand that the sensor element inside the housing does not come in contact with negative environmental influences such as dirt, oil and/or water. This necessitates that the cable bushing is designed such that it forms a tight seal against the housing as well as against the cable insulation.
From the Federal Republic of Germany Application No. 41 26 378 A1, a cable bushing is known for which the connecting cables are fed through an elastic, plug-like molded body. The molded body is composed of a temperature-resistant material, e.g. PTFE (TEFLON), and is enclosed and pressed together by a housing sleeve that forms the housing. An O-ring is additionally inserted as a seal between housing sleeve and molded body. The O-ring is composed of an elastomer, for example Viton, and has only a limited temperature stress tolerance. The use of this cable bushing at higher temperatures, such as are present if the gas sensor is arranged close to the motor exhaust, is therefore limited with respect to the temperature resistance of the seal.